Piette V, Lammerhofer M, Lindner W, Crommen J
Laboratory of Analytical Chemistry, University of Namur, Rue de Bruxelles, 61, B-5000 Namur, Belgium.
Chirality. 1999;11(8):622-30. doi: 10.1002/(SICI)1520-636X(1999)11:8<622::AID-CHIR3>3.0.CO;2-P.
A capillary electrophoretic (CE) method for the enantioseparation of N-protected chiral amino acids was developed using quinine and tert-butyl carbamoylated quinine as chiral selectors added to nonaqueous electrolyte solutions (NACE). A series of various N-derivatized amino acids were tested as chiral selectands, and in order to optimize the CE enantioseparation of these compounds, different parameters were investigated: the nature of the organic solvent, the combination of different solvents, the nature and the concentration of the background electrolyte, the selector concentration, the capillary temperature, and the applied voltage. The influence of these factors on the separation of the analyte enantiomers and the electroosmotic flow was studied. Generally, with tert-butyl carbamoylated quinine as chiral selector, better enantioseparations were achieved than with unmodified quinine. Optimum experimental conditions were found with a buffer made of 12. 5 mM ammonia, 100 mM octanoic acid, and 10 mM tert-butyl carbamoylated quinine in an ethanol-methanol mixture (60:40 v/v). Under these conditions, DNB-Leu enantiomers could be separated with a selectivity factor (alpha) of 1.572 and a resolution (Rs) of 64.3; a plate number (N) of 127,000 and an asymmetry factor (As) of 0.93 were obtained for the first migrating enantiomer.
开发了一种毛细管电泳（CE）方法，用于N-保护的手性氨基酸的对映体分离，该方法使用奎宁和叔丁基氨甲酰化奎宁作为手性选择剂添加到非水电解质溶液（NACE）中。测试了一系列不同的N-衍生化氨基酸作为手性被选择物，为了优化这些化合物的CE对映体分离，研究了不同参数：有机溶剂的性质、不同溶剂的组合、背景电解质的性质和浓度、选择剂浓度、毛细管温度和施加电压。研究了这些因素对分析物对映体分离和电渗流的影响。一般来说，以叔丁基氨甲酰化奎宁作为手性选择剂时，比未修饰的奎宁能实现更好的对映体分离。在由12.5 mM氨、100 mM辛酸和10 mM叔丁基氨甲酰化奎宁组成的缓冲液中，于乙醇-甲醇混合物（60:40 v/v）中发现了最佳实验条件。在这些条件下，DNB-Leu对映体可以以1.572的选择性因子（α）和64.3的分辨率（Rs）进行分离；对于第一个迁移的对映体，获得了127,000的塔板数（N）和0.93的不对称因子（As）。
